Elastic fluid turbine



April 12,' 1932. D. F. WARNER ELASTIC FLUID TURBINE Filed July 25, 1931Inventow: Donald F Wawnen M His Attowne Patented Apr. 12, 1932 UNITEDSTATES PATENT, OFFICE? DONALD IE. wAImEmoF LYnN, 'MAssAoHUsE'r'rs,AssIGNoR' USO GENERAL ELECTRIC COMPANY, AooRroRATIoN 0F NEWJYORK?ELASTIC FLUID TURBINE v r Application filed July 23,

' This invention relates to elastic fluid turbines wherein elastic fluidfroman extrac: tion stage or from the exhaust or from both anextractionstage and the exhaust is used for industrial purposes. Turbines of thiskind are :known .as'automatic extraction turbines, back pressureturbines and combined automatic extraction and'back pressure turbinesrespectively. 1 a

In these turbines it is desirable to control the flow of elastic fluidto the-turbine and from an extraction stage to the next lower stage interms of pressure in the extraction stage and in the exhaustrespectively.

The speed of such combined extraction and back pressure turbine maybemaintained constant by external means such as a line of constantfrequency to which anelectric genera-tor driven by said turbine isconnected in parallel with other electric generators. The mechanicalenergy which is transferred from such aturbine to the electric generatorat a determined speed depends upon theamount of steam extracted from theextraction stage and the amount of steam passing the exhaust.

The electric generator having a;,certain load capacity and being drivenby such a.tur-' bine is liable to be overloaded and damaged if themechanical energy transferred to the generator exceeds a certainsustained value or, in other words, if the demands for extraction andexhaust steam simultaneously reach certain'values, and particularly'ifboth extraction and exhaust steam demand reach a maximum value at thesame time.

. One object of my invention comprises an improved control mechanismwhich prevents overload of the electric generator driven by such turbineor, in other words, which limits the mechanical load output of suchturbine-to a predetermined value so long as initial conditions in thesteam or fluid at the throttle are maintained. I 7

Another object of my invention consists in the provision of'means whichrendervvalve opening actuation of certain pressure re:- sponsive. meansineffective 1f the mechanlcal load output of the turbine'h'asreachedsuch predetermined maximum value.

My invention accordingly comprises the tion when the mechanical loadoutput of the turbine fhas' reached'v a certain maximum value regardlessof therelative demands for extracted and exhausted steam andprovidinginitial steam or fluid conditions are maintained. My invention alsocomprises the provision of yieldable-connections between one or morepressure responslve dGVlCGS and a lever mechanism which connects suchde-f vices with the valve actuating means. i r

For a better understanding of what I be lieve to be novel-in myinvention attention is directed to the following description-and theclaims appended thereto. I 'Referring to the drawings,- Fig. 1illustrates a preferred embodiment of I my invention applied to acombined extraction: and

back pressureturbine; Fig. 2 illustrates a modified arrangementaccording to my in? vention, and Fig. 3- illustrates a diagrammatic viewof a part of Fig. 1 in different operative positions. 7 f T Referring toFig. 1,1 indicates the casing of an elastic fluid turbine, 2-indicatesthe shaft, and 3.-indicates' oneof the "bucket wheels. The turbineisillustrated as being viewed from the high; pressure end and is partlybroken away at different sections. 4

indicates a conduit for admitting elastic 1 fluid to the high pressureend of theturbine,

the admission of elastic fluid being controlled by a valve means 5. '6indicates the exhaustconduit for the turbine and 7"indicates'anextraction conduit connected to an interme- 'diate stage of the turbine;In the extraction stage is a valve means 8, a known form of ring valvebeing illustrated, which serves to.

control the flow of elastic fluid from the extraction stage to the nextlower stage. It is provided with a gear segment 9 with which meshes ashort rack 10 connected by a rod 11 to the piston 12 of a fluid-actuatedmotor. The pilot valve for the fluid-actuated motor is indicated at 13.WVhen ring valve 8 is turned in a clockwise direction it serves to shutoff the flow of elastic fluid from the extraction stage to the nextlower stage while when it is turned in a counterclockwise direction itis opened further to permit of increase in the flow of elastic fluidfrom the extraction stage to the next lower stage and to the exhaust.The ring valve is illustrated diagrammatically and by way of example,such arrangements being now known in the art. A valve means of this typeis more particularly illustrated and described in the pat- 2 ent toNorton 1,091,078, dated March 24,

14 indicates a pressure responsive device here shown as being in theform of a corrugated bellows located in a casing 15. Casing 15 isconnected by a pipe 16 to exhaust-conduit 6. Pressure responsive device14 is thus subjected to the exhaust-conduit pressure.

Connected to the pressure responsive device is a stem 17 which at itsupper end is 30 connected to one end of a floating lever 18. The otherend oflever 18 is connected to a speed governor 19 driven from theturbine shaft Spring 21 is a tension spring and operates in a directionto oppose the collapsing of corrugated bellows 14. The tension of thespring may be adjusted by turning the nut 20 in sleeve 20. When thepressure in exhaustconduit 6 increases, corrugated bellows 14 iscollapsed somewhat moving the left hand end of lever 18 upward, whilewhen the pressure decreases spring 21 serves to lower the left hand endof the lever 18. A rod 22is pivoted at its upper end tolever 18 and hasan abutment 22 at its lower end. A lever 23 is slidably secured at itsleft end to rod22. and is pressed against said abutment by a spring 22.The right end of said lever 23 is pivoted on a fixed fulcrum 24.Pivotally mounted on lever 23 is a bell crank lever comprising arms 25and 26. Arm 25 is connected by a link 27 to one end of a lever 28. Theother end of lever 28 is connected to a suitable fulcrum 29.

Lever 28 is connected by a link 30 to one end of a floating lever 31.The other end of floating lever 31 is connected to the stem 32 of afluid-actuated motor 33, the stem 34 of the pilot valve of thefluid-actuated motor being connected to floating lever 31 at anintermediate point. The stem 32 is connected to a valve disk 35 of valvemeans 5.

Lever 23 is connected by a rod 36 to one arm of a bell crank lever 37pivoted at the end of a bracket 38, the other arm being connected to oneend of a floating lever 39. The other end of floating lever 39 ispivotally connected to an intermediate point of a lever arm 40 pivotedat its lower end on bracket 41 and pivotally connected. at its upper endto a rod 42 which forms an extension of piston rod 11. The stem of pilotvalve 13 is connected to floating lever 39.

Bell crank lever arm 26 is connected by a link 43 to one arm of the bellcrank lever 44 pivoted on a fulcrum common also to lever 23 in line withits pivot 24; The other arm of bell crank lever 44 is pivotallyconnected to a stem 45 which at its lower end is connected to acorrugated bellows 46 similar to the corrugated'bellows 14. Corrugatedbellows 46 is located in a casing 47 which is connected by a pipe 48 tothe extraction stage conduit 7. Corrugated bellows 46 is thus subjectedto the pressure in the extraction stage. The collapsing of corrugatedbellows 46 is opposed by an adjustable tension spring 49 arranged in amanner similar to the spring 21.

Theoperation is as follows:

Assumethat the turbine is running, the speed being fixed by someexternal means and that valve means 35 and ring valve 8 are positionedso that the pressures in the extraction stage conduit and theexhaust-conduit are of the desired value. If now the pressure intheexhaust-conduit increases due to'a decrease in fluid demand, forexample, corrugated bellows 14 will be collapsed somewhat therebylifting the left hand end of lever 18 and through link 22 lifting theleft hand end of lever 23, the lever 23 turning on its pivot 24. Thisserves to lift the right hand endof lever 28 thereby lifting thepilotvalve offluid-actuated motor 33 so as to admit actuating fluid tothe upper side of the piston of the fluidactuated motor and permittingit to escape from the lower side. This causes the piston to movedownward thereby closing valve means 5 somewhat so as to decrease theamount of elastic fluid being admitted to the turbine. When the pistonof the fluid-actuated motor moves downward it lowers the right hand endof floating lever 31 thereby restoring the pilot valve to its formerposition. Also, when lever 23 moves upward, through rod '36 it turnsbell crank lever 37, moving pilot valve 13 toward the left. This servesto admit actuating fluid to the left hand side of piston 12 and permitsit to escape from the right hand side thereby moving piston 12 towardthe right and eifecting a closing movement of the ring valve 8. Whenpiston 12 moves toward the right the pilot valve is restored to itsformer position through lever arm 40 and the floating lever connection39.

If the pressure in exhaust conduit 6 decreases then spring 21 eflectsdownward movement of the left hand end of lever 18 and in a mannersimilar. to that already described, effects an opening movement ofvalvemeansband of the ring valve 8. Thus it will be seen that when theexhaust conduit pressure inoreases, lboth the high pressure valve meansand the ring valve means are closed somewhat, while when the exhaustconduit pressure decreases, both the high pressure, valve means and thering valve means are opened somewhat. 1 V

Upon a change in extracted'steam demand the extraction pressure-governor-457 acts torotate bell crank 44 which in turn rotates bell crank 2526in a likeirotary direction. A decrease in extracted steam demand causesan increase in stage pressure. The extraction governor bellows travelsin a direction toward its high pressure'stop. This causes a clockwisemovement of the bell cranks, as shown in the drawings. Upward movementof link27 acts through lever 28, pilot valve 34, piston and rod 32, etc.to move the main controlling valves in a-direction toward closing. Thegrid valve 8 remainsundi'sturbed by any action of the extractiongovernor so that if, as assumed in this case, constant demand forexhausted steam exists, the flow and pressure at the exhaust will beunchanged asit should be. The pressure governor 14 etc. therefore holdslever 23 in a fixed 'position'during a change in demand for extractedsteam only. Thus it is seen that a change in extracted steam demand canoccur without disturbance to the conditions at the exhaust of theturbine.

The mechanism so far described may be taken as typical for the controlof a combined extraction and back pressure turbine in which loadlimiting device and a yieldable connection with respectto one pressureresponsive device may be provided for the purpose here'- inafter setforth. ,Whereas I have described such a combined extraction and backpressure turbine as comprising asingle unit, wish to have it understoodthat such turbine may also comprise two separate units, a high and a'lowpressure unit, mechanically cou-' pled and driving the same generator orgenerators. My'invention also is not limited to steam turbines as itmaysimilarly be applied to other. elastic fluid engines, such as mercuryvapor turbines. V a i According to my invention I provide a mechanicalload-limiting device which, as already pointed out, automaticallyprevents further valve opening action when the. mechanical load outputof the turbine has reached a predetermined value. a

This load-limiting device may be provided with respect to a part of thecontrol mechanism, the movement'of which is a function of themechanical'load output of theturbine. More particularly I provide theload-limiting device at a definite point of such part of the controlmechanism, the movement of whichis a function of the mechanical loadoutput and not to any appreciable degree affected by the ratio of flowsfrom the exhaust and extraction points. U e

The movements of such part have to satisfy certain conditions which willbe more readily understood from the following:

Let us assume that an amount ofsteam- (A+B) vbe admitted to the turbine,an

amount of steam A be extracted from an intermediate stage and an amount1 be passed through the low pressure part the turbine.

Thethermo-dynamic energy of.

the steam passing through the turbine partly transformed into mechanicalenergy.

steam amount pressure part of the turbine is. proportional to the amountA itself and a constant 0 The mechanical energy M 'obtained from the Apassing through the high be a function of the amount A, the pressuredrop within the For certain conditions such constant will have adefinite numerical value whichmay change if one of said conditionschanges." This constantmay also be considered as the efficiency factoror the coefficient of transformation (hereafter termed transformationfactor) of the high'pressure part of the turbine.

turbine, temperature, etc..

In a similar manner the mechanical ens ergy M obtainedfromthe steamamountB the entire turbine is,

M B I wherein a is a corresponding constant wit respect to the entireturbine.

passing through The total mechanical load output isequal to the sumofthe mechanical energies obtained from both amounts of steam A and I B.Thus, M=M +M ,or,' introducing the above equations, M=c A+c B Inasimilar manner it can be proven that. V

wherein o and 0 represent the transformation factors of the highpressure and the low pressure part. respectively .and wherein (A+B) isthe amount of steam passing the high pressure part and-B is the amountof steam passing the low pressure part.

Referring to the last equation M=0,. A+B +'@1B it will be seen that inthe equation c (A+B) represents the output of the ing the extractionopening (M 0 (B) represents the output ofthe stages following theextraction opening (M The equation also indicates a mutual actuation ofthe lever mechanism under certain conditions. In

stages precedcase the steam demand B of the exhaust changes, it causesan actuation of both the admission valve and the valve before the quiredto find that part of the mechanism 7 which acts as a real or imaginaryfulcrum during changes in the relative demands for steam at theextraction opening and at the exhaust during which a constant mechanicalload output M is being delivered. If now, a point in the lever mechanismcan be found such that a motion m corresponds to a mechanical loadoutput change M in the stage or stages preceding the extraction 7opening, andsuch that a motion m corresponds to a mechanical load outputchange M in thestage or stages following the extraction opening. Thenwherein I0 and are factors of the lever mechanism involving theefliciencies of the stages preceding and following the extractionopening respectively, and physical characteristics of the governingmechanism.

If a definite flow of steam B passing or in another form,

ex k2 C]; A B

or ass This result shows that the part of the lever mechanism where theload limiting device has to be applied must satisfy the conditionaccording to which the ratio &

2 is inversely proportion to the corresponding ratio of thetransformation factors.

A point which substantially satisfies this condition is located on thehorizontal part 25 of bell crank lever 25, 26under the assumption thatthe transformation factors 0,, and 0 are linear functions of the steamamounts A and B respectively and the corresponding physical conditionwhich in fact is approximately true within certain limits.

In the present instance I have shown a load-limiting device between saidlever 25 in the simplest form as comprising a fixed plate 50 and anadjustable head screw 51. p

It will be understood that there is only one point beneath said lever towhich a definite ratio applies. Thus, a displacement of the screw ineither direction along the length of the lever would correspond to achange of such ratios. In order to make this important feature clear,attention is directed to Fig. 3 in which I have illustrated a part ofthe lever mechanism in difierent operative positions with respect to aload-limiting device. AB and CD represent levers corresponding to levers23 and 25 of Fig. 1' respectively, and S indicates the load-limitingdevice.

Let us assume that the turning movements are such that in a change ofdisposition of the levers represented by a ,8 and a ,8 occurs withoutchange in mechanical load output. The levers AB and CD in thesepositions are indicated by A 13. A B and C D C D In such an event theintersection point along the horizontal arm C-D of the bell crank leveris the proper location for the abutment if the load is to be limited tothat value. It is shown as preventing any further downward travel of thelever C-D. It, therefore, limits governor travel in a valve-openingdirection. The governor limiting device S as shown in Fig. 3 is properlyset as there is no change in mechanical load output caused by rotationof the lever CD about the point of engagement of the lever with thelimiting abutment.

In any other application the relative location of S relative to lever CDhas to be changed in dependanceupon thetransformation factors of thestages preceding and the stages following the extraction opening, andthe physical characteristics of the two valve groups and the design ofthe interconnecting linkage and lever system.

Only the properly applied load-limiting device maintains the maximummechanical load output substantially constant regardless of the relativesteam demand in the high pressure and low pressure part.

If the total load of the turbine reaches a predetermined value and vitalsteam conditions being assumed constant, lever 25 engages the screw 51which prevents further opening of valve and limits thereby auto--matically the total load of the turbine. This limiting action takesplace regardless of the relative demand for extracted and exhaust steam.

At such times when the horizontal arm is in abutment with theload-limiting device (50, 51) it is desired to render further valveopening action of the back pressure governor ineffective. This isachieved bythe yielding connection 22 between the levers 18 and 23.

A decreasingsteam pressure in the exhaust pipe effects the pressureresponsive device 14 to move the left end of lever 18 downward- 1y. Butthis movement is not transferred to lever 27 as rod 22 merely slidesdownwardly within the end of lever 23, pressing spring 22 together.

In connection with the operation of the mechanism it will be understoodthat the lever arm and the connections are so chosen relatively to eachother that when lever arm 23 is moved valve means 5 and valve means 8are opened or closed by amounts such that valve means Swill normallyefiect an increase or decrease of flow past it corresponding to thechange in flow past valve means 5.

If the pressure in the extraction stage conduit increases bellows 46 iscollapsed some- I what thereby turning bell crank lever 44 in aclockwise direction and through link 43 turning the bell crank levercomprising arms 25 and 26 in a clockwise direction. This serves to liftthe pilot valve of fluid-actuated motor 33 thereby efiecting a closingmovement of the valve means 5 to decrease the amount of elastic fluidadmitted to the turbine and bring thepressure in the extraction stageback to its equilibrium value, which is V substantially its formervalue.

If the pressure in the extraction stage decreases then spring 49 servesto turn bell crank lever 44 in a counterclockwise direction, therebyeffecting an opening movement of valve means 5 so as to restore thepressure to its equilibrium value. When the pressure in the extractionstage varies, it-willbe'seenthat no adjustment of the stage valve meanstakes place, the high pressure valve'means only being moved to bring theextraction stage pressure back to normal value. As a result the pressurein the exhaust-conduit will tle and to decrease the flowtoexhaust. Theload will be maintained at the limit.- It is,

therefore, seen that the increased extraction demand is satisfied andwithout an increase in load. It will be further seen that this is acinthe extraction" complished by means of reducing further the flow toexhaust, which when the abutment is made is already limited to a valuebelow that necessary to satisfy the existing demand.

A similar action takes place when a depressure rises in the extractionstage, when the lever 25 is in abutment with the governor limit;

Y a In other words, when the yielding link is applied to the link22extraction demand is satisfied at the expense of exhaust demand whenthe governor is in abutment.

c crease in extracted steam demand occurs and- In the event that it is.desirable to satisfy a the exhaust demand at the expenseof theextracted steam demands "at times when the governor is in abut-ment'itwould be neces sary to apply the yielding connection to the extractionpressure governor element. 1

There are also cases in which yieldable connections may be provided.with respect to both the intermediate stage and the exhaustresponsivemeans. In Fig; 2,I have illustrated such an arrangement; likereference I charactersdesignatethe same parts as in Fig. 1. Link 17which is positioned by' the inter mediate stage responsive device, isslidable in a hole of the left end of lever Band has an abutmentnormally pressed against lever 18 by the action of a spring 17 6. Link45, shown at the right side of the drawings, which ispositloned by theextraction responsive device, is similarly slidable in a hold providedin one arm of thebell crank lever 44, andhas an abutment 45a normallypressed against the bell icrank leverby the action .of a spring 455.;The operation of this mechanismislthe.

same as that described above, with the exception that it allows a freepositioning of the extraction responsivedevice 46 (see F ig.1 when lever28 is in abutment position;

In accordance withthelprovisionsof the PatentStatutes', I havedescribedthelprinciple of. operation ofmy invention, together V I withthe apparatus which I now considerto represent the best embodimentthereof, but

I de'sir'eto' have it understood thatthe appara-' tfus'shown is onlyillustrative and thatthe invention may be carried out by other mean's,

What I claim as new and desire to' secure by Letters Patent of theUnited States is:

1. The combination with an elasticfluid turbine, a conduit connected toan intermediate stage of said turbine, another conduit connected to theexhaust of said turbine, pressure responsive devices connected to saidintermediate stage and. said exhaust r'espelc tively, avalve mechanismcontrolling the ad,- mission of elastic fluid to the turbine,la valvemechanism controlling the flow of elastic fluid to the-exhaust of theturbine, both being adjusted by said pressure responsive devices, 7

and means for limiting the opening action of a both valve mechanisms atsuch times when the iao Ill

nszseooe mechanical loa'd output of said: turbine: has: ableloadrlimiti-ngrmeansis in; abutmenirposie reached av predeterminedvalue.

' 2; The combination with an elastic fluid: turbine, a conduit to anintermediate stage of said turbine, another conduit to the exhaustofsaid turbine, pressure responsive devicesconnected tosaid intermediatestage and said exhaust respectively, a valve mechanism controlling theadmission of elastic fluid to the, turbine, a valve mechanismcontrolling the flow of elastic fluid to the exhaust of the turbine,both being adjusted by said pressure responsive devices, means forlimiting the openingaction of, both valve mechanisms in response to thedemands for steam at either tion;

' hand;

the; extraction opening or at the: exhaust of the turbine, said limitingmeans being provided at a part of the valve. mechanism the motions ofwhich with respect to the mechanical energies obtained from the steamamounts leaving the intermediate stage and exhaust espectively, areinversely proportional to the corresponding transformation factors ofthe turbine with regard to'said steam. amounts.

The combination with an elastic fluid turbine having aconduitconnectedto an intermediate stage, valve means controllingtheflow of elastic fluid to the turbine, and valve means controlling theflow of elastic fluid' tromsaid intermediate stage to the next lowerstage, of means responsive to a condition ap-- purtenant to the exhaustleaving the turbine for effecting adjustment of both said valve.

means in: the same direction, means responsive to a conditionappurtenant to elastic fluid flowing in said conduit forefl'ectingadjusu ment of said first-named valve means only, andadjustable means adapted to limit the opening of said valve meanscontrolling the flow of elastic fluid to the turbine in response todemands for elastic fluid at the extraction opening and at the exhaust.

- 4:. The. combination with an'elastic fluid turbine having a conduitconnected to an intermediate stage, valve means controlling the flow ofelastic fluid to the turbine and valve means controlling the flow ofelastic fluid from-said intermediate stage tothe next lower stage, of alever means connecting both said valve means whereby when said lever ismoved both valve means are adjusted in the same direction, meansresponsive to a condition appurtenant to the exhaust leaving the turbinefor moving said lever, means responsive to a condition appurtenant toelastic fluid flowing in said conduit for 'eflecting adjustment of saidfirst-named valve means independently of said second-named valve means,means forming a yieldable connection between said lever and said meansresponsive to the exhaust conditions, and adjustable means adapted tolimit the opening-travel of said lever, said yieldable connecting meansbeing adapted to render the action ofsaid exhaust responsive meansineflective if. said adjust- I-n; witnessgwhereoff I: haveherenntdsatiny;

DONALD F. WARNER;

